Hello student,

These are all the things that you can do after B.Tech in Mechanical Engineering..

1. Get placed at a great core company.. Work hard to slowly rise through the ranks.
2. Get placed at a not so good core company. Work hard to get a job at the above mentioned companies.
3. Get placed at an IT company. Forget that you ever were a mechanical engineer and embrace the world of computers.
4. Give GATE. Land a job in one of the PSUs.
5. Give GATE. Pursue an Mtech (preferably in a college more reputed than your Btech one).
6. Decide that you need to have a 'foreign' education. Give GRE and get into a US university.
7. Decide that you want to pursue a career in academics/research/teaching. Give GRE, get a scholarship and get into a five (or more) year integrated MS and PhD program in a reputed college in the US.
8. Sit for CAT. This a cyclic process, remember. Continue doing this until you get a college of your choice or settle down for the one you are getting.
9. Forget everything you have learnt in college and do something radically different, be it starting up, or becoming an author/photographer/musician/....
10. Get a job in any of the companies mentioned in 1 to 3. Get frustrated to no end. Decide that enough is enough. After one or two years, do any of the things from points 4 to 9.